Method of manufacturing microlens array substrate, microlens array substrate, electro-optic device, and electronic

ABSTRACT

There is provided a method of manufacturing a microlens array substrate with improved manufacturing yield and high quality, the method including: forming a groove part along an outer edge of a first area on a surface of a substrate; forming a mask layer to cover a side of the surface, forming a plurality of openings in the first area, and forming openings along the outer edge of the first area; performing isotropic etching on the substrate through the mask layer, forming a plurality of recesses in the first area, and forming recesses across a boundary part between the first area and the groove part; removing the mask layer from the substrate; forming a light transmission material layer that has a refractive index, which is different from a refractive index of the substrate, to cover the side of the surface of the substrate and to bury the plurality of recesses; and planarizing an upper surface of the light transmission material layer.

BACKGROUND

1. Technical Field

The present invention relates to a method of manufacturing a microlensarray substrate, a microlens array substrate, an electro-optic device,and an electronic apparatus.

2. Related Art

An electro-optic device, which includes an electro-optic material (forexample, liquid crystal or the like) between an element substrate and acounter substrate, has been known. For example, a liquid crystal device,which is used as a liquid crystal light valve of a projector, can bedescribed as the electro-optic device. In such a liquid crystal device,it is required to realize high light use efficiency. Here, aconfiguration has been known in which, when the liquid crystal deviceincludes a microlens array substrate, light incident to the liquidcrystal device is condensed and light, shielded by a light shieldinglayer if the light is not condensed, is used, and thus a substantialopening ratio of the liquid crystal device is improved.

The microlens array substrate includes a substrate in which a pluralityof recesses are formed on a surface and which is formed of quartz, and alens layer which is formed to cover the substrate and which has arefractive index different from that of the substrate. In the microlensarray substrate, a plurality of microlenses are formed by burying theplurality of recesses in the substrate using a lens layer. The lenslayer is formed of a resin material or an inorganic material, and anupper surface of the lens layer is planarized by providing, for example,a cover member, or performing a planarizing process such as a ChemicalMechanical Polishing (CMP) process.

However, with regard to a display area in which the plurality ofrecesses are formed to be dug down from the surface of the substrate,the upper surface of the lens layer is high in a peripheral area, whichis on the outer side of the display area and in which the recesses arenot formed, and thus a step is generated on the upper surface of thelens layer. If the step on the upper surface of the lens layer is large,the increase in man hour or the deterioration in evenness of the uppersurface of the lens layer is caused when the planarizing process isperformed on the upper surface of the lens layer.

In contrast, a method of manufacturing a microlens array substrate (forexample, refer to JP-A-2009-294363) is proposed to reduce the differencein thickness of a lens layer (resin layer), that is, to reduce a step onan upper surface of the lens layer by providing a groove part (depressedpart) in a peripheral area (lens non-formation area) of a substrate andlowering the height of a non-display area than that of a display area(lens formation area) of the substrate.

According to the manufacturing method disclosed in JP-A-2009-294363, wetetching is performed on the substrate through a mask layer (first hardmask film) which covers only the display area of the substrate, thegroove part, which is depressed toward a lower part than the substratesurface of the display area, is formed in the peripheral area, and thenthe mask layer is removed. Further, the wet etching is performed on thesubstrate through a mask layer (second hard mask film), which covers thewhole surface of the substrate and in which a plurality of openings areprovided in the display area, a plurality of recesses are formed in thedisplay area, and then the mask layer is removed.

However, in the manufacturing method disclosed in JP-A-2009-294363,before the mask layer (second hard mask film) is formed to form theplurality of recesses in the display area, a step is formed by thegroove part in the boundary of the display area and the peripheral areaof the substrate. Therefore, when the mask layer (second hard maskfilm), which is formed on the whole surface of the substrate, isremoved, there is a problem in that a part of the mask layer is notremoved and remains at a corner of the step, more specifically, a cornerof the bottom surface and the side wall of the groove part. When a partof the mask layer remains, there are cases in which an upper lens layeris peeled together with the remaining mask layer and in which cracksappear in the lens layer because stress is applied to the remaining masklayer. Therefore, a method of manufacturing the microlens arraysubstrate is required which is capable of performing removal such thatthe mask layer, which is necessary to form the plurality of recesses,does not remain in the display area even when the groove part isprovided in the peripheral area of the substrate in order to reduce thestep on the upper surface of the lens layer.

SUMMARY

The invention can be implemented as application examples.

Application Example 1

According to this application example, there is provided a method ofmanufacturing a microlens array substrate in which a plurality ofmicrolenses are arranged in a first area, the method including: forminga groove part along an outer edge of the first area on a first surfaceof a substrate; forming a first mask layer to cover a side of the firstsurface of the substrate, forming a plurality of first openingscorresponding to the plurality of microlenses in the first area of thefirst mask layer, and forming second openings along the outer edge ofthe first area; performing isotropic etching on the substrate throughthe first mask layer, forming a plurality of first recessescorresponding to the plurality of first openings in the first area, andforming second recesses corresponding to the second openings across anedge part on a side of the first area of the groove part; removing thefirst mask layer from the substrate; forming a light transmissionmaterial layer that has a refractive index, which is different from arefractive index of the substrate, to cover the side of the firstsurface of the substrate and to bury the plurality of first recesses andthe second recesses; and planarizing an upper surface of the lighttransmission material layer.

In the manufacturing method according to the application example, thegroove part is formed along the outer edge of the first area in whichthe plurality of microlenses are arranged. Therefore, if the lighttransmission material layer is formed to cover the side of the firstsurface of the substrate and to bury the plurality of first recesses, astep between the first area, which is generated on the upper surface ofthe light transmission material layer and a peripheral area thereof inwhich the groove part is formed, is reduced and is less than a stepbetween the first surface of the substrate and the groove part, comparedto a case in which the groove part is formed in the outer edge of thefirst area. Therefore, in the planarizing of the upper surface of thelight transmission material layer, it is possible to reduce man hourwhen the planarizing is performed, and it is possible to improveevenness on the upper surface of the light transmission material layer.

Further, in the performing of the isotropic etching on the substratethrough the first mask layer and forming the plurality of first recessesin the first area, the second recesses are formed across the edge parton the side of the first area of the groove part. Therefore, in aportion where the second recesses are formed at a corner of a step ofthe first surface of the substrate and the groove part, that is, at acorner of the bottom surface and a side wall of the groove part, acavity part is generated on a lower side of the first mask layer.Therefore, in the removing of the first mask layer from the substrate,it is possible to properly remove the first mask layer even at thecorner of the bottom surface and the side wall of the groove part.Therefore, it is possible to provide the method of manufacturing themicrolens array substrate, which is capable of removing the first masklayer such that a part of the first mask layer does not remain even whenthe groove part is provided in the outer edge of the first area in orderto reduce the step on the upper surface of the light transmissionmaterial layer.

Application Example 2

In the method of manufacturing the microlens array substrate accordingto the application example, the forming of the groove part may include:forming a second mask layer that covers the first area of the firstsurface of the substrate; forming the groove part by performinganisotropic etching on the substrate through the second mask layer; andremoving the second mask layer.

In the manufacturing method according to the application example, whenthe anisotropic etching is performed on the substrate through the secondmask layer which covers the first area, the groove part is formed alongthe outer edge of the first area. Therefore, compared to a case in whichthe isotropic etching is performed, the evenness of the bottom surfaceof the groove part is improved, and thus it is possible to improve theevenness of the upper surface of the light transmission material layerwhich is formed to cover the side of the first surface of the substrate.In contrast, since the groove part is formed by performing theanisotropic etching, the corner of the bottom surface and the side wallof the groove part is steep compared to the case in which the groovepart is formed by performing the isotropic etching. Therefore, in theremoving of the first mask layer from the substrate, a part of the firstmask layer easily remains at the corner of the bottom surface and theside wall of the groove part. However, since the cavity part isgenerated on the lower side of the first mask layer at the corner due tothe second recesses, it is possible to perform removing such that a partof the first mask layer does not remain at the corner.

Application Example 3

In the method of manufacturing the microlens array substrate accordingto the application example, the removing of the first mask layer mayinclude performing anisotropic etching on the first mask layer.

In the manufacturing method according to the application example, thefirst mask layer is removed by performing the anisotropic etching.Therefore, compared to the case in which the isotropic etching isperformed, a part of the first mask layer is prone to remain at thecorner of the bottom surface and the side wall of the groove part.However, since the cavity part is generated on the lower side of thefirst mask layer at the corner due to the second recesses, it ispossible to perform removing such that a part of the first mask layerdoes not remain even when the anisotropic etching is performed.

Application Example 4

In the method of manufacturing the microlens array substrate accordingto the application example, the second openings may be arranged toextend along the outer edge of the first area.

In the manufacturing method according to the application example, thesecond openings are arranged to extend along the outer edge of the firstarea in the first mask layer. Therefore, since the second recesses areformed to extend along the outer edge of the first area on the lowerside of the first mask layer at the corner of the bottom surface and theside wall of the groove part, the cavity part which extends to the lowerside of the first mask layer is generated at the corner. Therefore, itis possible to properly remove the first mask layer at the corner of thebottom surface and the side wall of the groove part.

Application Example 5

In the method of manufacturing the microlens array substrate accordingto the application example, the forming of the second openings mayinclude forming a plurality of second openings along the outer edge ofthe first area, and an interval between the plurality of second openingsmay be smaller than an interval between the plurality of first openings.

In the manufacturing method according to the application example, theplurality of second openings are arranged along the outer edge of thefirst area of the first mask layer, and the interval between the secondopenings is smaller than the interval between the first openings.Therefore, the plurality of second recesses are formed on the lower sideof the first mask layer at the corner of the bottom surface and the sidewall of the groove part along the outer edge of the first area in higherdensity than the first recesses. Therefore, since the cavity part whichis connected to on another due to the plurality of second recesses isgenerated at the corner of the bottom surface and the side wall of thegroove part, it is possible to further properly remove the first masklayer.

Application Example 6

In the method of manufacturing the microlens array substrate accordingto the application example, the second openings may be arranged in anarea which is overlapped with the groove part in a planar view.

In the manufacturing method according to the application example, in thefirst mask layer, the second openings are arranged in the area which isoverlapped with the groove part in a planar view. That is, the secondopenings are provided on the bottom surface of the groove part which isa lower part than the first openings provided on the first surface ofthe substrate. Therefore, compared to a case in which the secondopenings are arranged in the first area, it is possible to form thesecond recesses, which are formed to correspond to the second openings,in a part lower than the corner of the bottom surface and the side wallof the groove part, and thus it is possible to cause the cavity part onthe lower side of the first mask layer at the corner to be larger.Therefore, it is possible to more properly remove the first mask layerat the corner of the bottom surface and the side wall of the groovepart.

Application Example 7

In the method of manufacturing the microlens array substrate accordingto the application example, a distance between a boundary part and thesecond openings may be equal to or less than a difference between a stepof the first surface and the groove part and a depth of the firstrecess.

In the manufacturing method according to the application example, thedistance between the boundary part of the first area and the groove partand the second openings which are arranged in the groove part is equalto or less than the difference between the step of the first surface andthe groove part and the depth of the first recess. That is, the secondopenings are arranged in a position in the vicinity of the corner of thebottom surface and the side wall of the groove part. Therefore, it ispossible to form the second recesses while the position which is in thevicinity of the corner of the bottom surface and the side wall of thegroove part is used as a central position, and thus it is possible tomore properly remove the first mask layer at the corner.

Application Example 8

In the method of manufacturing the microlens array substrate accordingto the application example, the second openings may be arranged in thefirst area.

In the manufacturing method according to the application example, thesecond openings are arranged in the first area of the first mask layer.That is, the second openings are formed at the same height as the firstopenings which are provided on the first surface of the substrate.Therefore, in a case of exposure when the first openings and the secondopenings are formed in the first mask layer, a distance from an exposuremachine to a position in which the openings are formed can besubstantially the same between the first openings and the secondopenings. Therefore, the positions of the second openings and theprecision in a size of a diameter can be the same as those of the firstopenings.

Application Example 9

According to this application example, there is provided a microlensarray substrate including: a substrate; a plurality of first recessesthat are provided in a first area of a first surface of the substrate; agroove part that is provided along an outer edge of the first area;second recesses that is provided across a boundary part between thefirst area and the groove part; and a light transmission layer that hasa refractive index, which is different from a refractive index of thesubstrate, and that is provided to cover the first surface of thesubstrate and to bury the plurality of first recesses and the secondrecesses.

In the microlens array substrate according to the application example,the groove part is provided along the outer edge of the first area inwhich the plurality of first recesses are provided. Therefore, if thematerial of the light transmission layer is accumulated to cover theside of the first surface of the substrate and to bury the plurality offirst recesses in the manufacturing the microlens array substrate, astep between the first area, which is generated on the upper surface ofthe material of the light transmission layer, and a peripheral area inwhich the groove part is formed is reduced and becomes small due to astep between the first surface and the groove part of the substrate,compared to a case in which the groove part is not formed in the outeredge of the first area. Therefore, it is possible to reduce man hourwhen a planarizing process to planarize the upper surfaces of theaccumulated materials of the light transmission layer is performed andit is possible to improve the evenness of the upper surface of the lighttransmission material layer.

Further, the second recesses are provided across the boundary part ofthe first area and the groove part. Therefore, when the first recessesand the second recesses are formed through the mask layer and then themask layer is removed, a cavity part is generated toward a lower side ofthe mask layer in a portion in which the second recesses are provided ata corner of the step of the first surface and the groove part of thesubstrate, that is, at a corner of a bottom surface and a side wall ofthe groove part. Therefore, it is possible to properly remove the masklayer even at the corner of the bottom surface and the side wall of thegroove part. Therefore, it is possible to improve the evenness of theupper surface of the light transmission layer, and it is possible toprovide the microlens array substrate with improved manufacturing yieldand high quality.

Application Example 10

According to the application example, there is provided an electro-opticdevice including: a first substrate; a second substrate that is arrangedto face the first substrate; an electro-optic layer that is arrangedbetween the first substrate and the second substrate; and the microlensarray substrate according to the application example that is provided onat least one of the first substrate and the second substrate.

In the electro-optic device according to the application example, sincethe electro-optic device includes the light transmission layer in whichthe evenness of the upper surface is improved and includes a themicrolens array substrate which has improved manufacturing yield andhigh quality on at least one of the first substrate and the secondsubstrate, it is possible to provide an electro-optic device with highquality and brightness.

Application Example 11

According to this application example, there is provided an electronicapparatus including the electro-optic device according to theapplication example.

In the electronic apparatus according to the application example, it ispossible to provide an electronic apparatus with high quality andbrightness.

BRIEF DESCRIPTION OF THE DRAWINGS

The invention will be described with reference to the accompanyingdrawings, wherein like numbers reference like elements.

FIG. 1 is a schematic plan view illustrating a configuration of a liquidcrystal device according to a first embodiment.

FIG. 2 is an equivalent circuit diagram illustrating an electricalconfiguration of the liquid crystal device according to the firstembodiment.

FIG. 3 is a schematic cross-sectional diagram illustrating theconfiguration of the liquid crystal device according to the firstembodiment.

FIGS. 4A to 4D are schematic cross-sectional diagrams illustrating amethod of manufacturing a microlens array substrate according to thefirst embodiment.

FIGS. 5A to 5D are schematic cross-sectional diagrams illustrating themethod of manufacturing the microlens array substrate according to thefirst embodiment.

FIGS. 6A and 6B are schematic diagrams illustrating a configuration of afirst mask layer which is used in a process to manufacture the microlensarray substrate according to the first embodiment.

FIGS. 7A and 7B are schematic diagrams illustrating a configuration of afirst mask layer which is used in a process to manufacture a microlensarray substrate according to a second embodiment.

FIG. 8 is a schematic diagram illustrating a configuration of aprojector as an electronic apparatus according to a third embodiment.

FIGS. 9A and 9B are schematic cross-sectional diagrams illustrating amethod of manufacturing a microlens array substrate according to a firstmodification example.

FIGS. 10A and 10B are diagrams illustrating a comparative example.

DESCRIPTION OF EXEMPLARY EMBODIMENTS

Hereinafter, embodiments which implement the invention will be describedwith reference to the accompanying drawings. The accompanying drawingsare displayed by being appropriately enlarged, reduced, or exaggeratedsuch that a portion to be described is in a recognizable state. Inaddition, there is a case in which unnecessary components fordescription are not shown in the drawing.

Meanwhile, in forms below, a case of a description of, for example, “ona substrate” indicates a case in which a substance is arranged to comesinto contact with the substrate, a case in which the substance isarranged on the substrate through another component, and a case in whichthe substance includes a part that is arranged to come into contact withthe substrate and the part is arranged through another component.

First Embodiment Electro-Optic Device

Here, as an electro-optic device, an active matrix type liquid crystaldevice which includes a Thin Film Transistor (TFT) as a switchingelement for a pixel will be described as an example. The liquid crystaldevice can be suitably used as, for example, an optical modulationelement (liquid crystal light valve) of a projection type displayapparatus (projector) which will be described later.

First, a liquid crystal device as an electro-optic device according to afirst embodiment will be described with reference to FIGS. 1, 2, and 3.FIG. 1 is a schematic plan view illustrating a configuration of theliquid crystal device according to the first embodiment. FIG. 2 is anequivalent circuit diagram illustrating an electrical configuration ofthe liquid crystal device according to the first embodiment. FIG. 3 is aschematic cross-sectional diagram illustrating the configuration of theliquid crystal device according to the first embodiment. Morespecifically, FIG. 3 is a schematic cross-sectional diagram illustratingtaken along a line III-III of FIG. 1.

As shown in FIGS. 1 and 3, an liquid crystal device 1 as theelectro-optic device according to the first embodiment includes anelement substrate 20 as a first substrate, a counter substrate 30 as asecond substrate which is arranged to face the element substrate 20, anda liquid crystal layer 40 as an electro-optic layer which is arrangedbetween the element substrate 20 and the counter substrate 30. As shownin FIG. 1, the element substrate 20 is greater than the countersubstrate 30, and both the substrates are bonded to each other through asealing material 42 which is arranged in a frame shape along an edgepart of the counter substrate 30.

The liquid crystal layer 40 is formed of liquid crystal which is sealedin a space surrounded by the element substrate 20, the counter substrate30, and the sealing material 42 and which has positive or negativedielectric anisotropy. The sealing material 42 includes, for example, anadhesive agent such as a thermosetting or ultraviolet curable epoxyresin or the like. The sealing material 42 is provided with a spacer(not shown in the drawing) for holding a uniform interval between theelement substrate 20 and the counter substrate 30.

Light shielding layers 22, 26, and 32 which include a frame-shapedperipheral part are provided in the inner side of the sealing material42 which is arranged to have the frame shape. The light shielding layers22, 26, and 32 are formed of, for example, light shielding metal ormetallic oxide. The inner sides of the light shielding layers 22, 26,and 32 correspond to a display area B, in which a plurality of pixels Pare arranged. The pixels P have, for example, a substantiallyrectangular shape and are arranged in a matrix shape.

The display area B is an area which substantially contributes to displayin the liquid crystal device 1. The light shielding layers 22 and 26 areprovided in, for example, a lattice shape along the boundary of adjacentpixels P in the display area B. Meanwhile, the liquid crystal device 1may include a dummy area which is provided to surround the periphery ofthe display area B on the outside (outer peripheral end side) of thedisplay area B.

On a side opposite to the display area B of the sealing material 42which is formed along a first side of the element substrate 20, a dataline drive circuit 51 and a plurality of external connection terminals54 are provided along the first side. In addition, on a side of thedisplay area B of the sealing material 42 along a second side which isopposite to the first side, an inspection circuit 53 is provided.Further, scan line drive circuits 52 are provided on the inner side ofthe sealing material 42 along another two sides which are perpendicularto the two sides and which are face to each other.

On the side of the display area B of the sealing material 42 of thesecond side on which the inspection circuit 53 is provided, a pluralityof wirings 55, which connect the two scan line drive circuits 52, areprovided. The wirings which are connected to the data line drive circuit51 and the scan line drive circuits 52 are connected to the plurality ofexternal connection terminals 54. In addition, vertical conduction units56 are provided at the corners of the counter substrate 30 forelectrical conduction between the element substrate 20 and the countersubstrate 30. Meanwhile, the arrangement of the inspection circuit 53 isnot limited thereto, and may be provided in a position along the innerside of the sealing material 42 between the data line drive circuit 51and the display area B.

In the description below, a direction along the first side on which thedata line drive circuit 51 is provided is an X direction as a firstdirection, and a direction along the other two sides which areperpendicular to the first side and face each other is a Y direction asa second direction. The X direction is a direction taken along a lineIII-III of FIG. 1. In addition, a direction which is perpendicular tothe X direction and the Y direction and which face an upper side in FIG.1 is a Z direction. Meanwhile, in the specification, a view of theliquid crystal device 1 from a normal line direction (Z direction) of asurface of an outside of the counter substrate 30 is called “planarview”.

As shown in FIG. 2, in the display area B, scan lines 2 and data lines 3are formed to cross each other, and the pixels P are provided tocorrespond to the cross of the scan lines 2 and the data lines 3. Eachof the pixels P is provided with a pixel electrode 28, and a TFT 24 as aswitching element.

The TFT 24 includes a source electrode which is electrically connectedto the data line 3 extended from the data line drive circuit 51. Imagesignals (data signals) S1, S2, . . . , Sn from the data line drivecircuit 51 (refer to FIG. 1) are line sequentially supplied to the dataline 3. The TFT 24 includes a gate electrode which is a part of the scanline 2 extended from the scan line drive circuits 52 (refer to FIG. 1).Scan signals G1, G2, . . . , Gm from the scan line drive circuits 52 areline sequentially supplied to the scan line 2. The TFT 24 includes adrain electrode which is electrically connected to the pixel electrode28.

The image signals S1, S2, . . . , Sn are written in the pixel electrode28 through the data line 3 at a predetermined timing by causing the TFT24 to be an on state only for a uniform period. In this manner, theimage signal, which is written in the liquid crystal layer 40 (refer toFIG. 3) through the pixel electrode 28 at a predetermined level, is heldin a liquid crystal capacity, which is formed between common electrodes34 (refer to FIG. 3) provided in the counter substrate 30, for a uniformperiod. When a voltage signal is applied to liquid crystal of each pixelP, a liquid crystal oriented state changes based on a level of theapplied voltage. Therefore, light which is incident to the liquidcrystal layer 40 is modulated, and thus tone display is possible.

Meanwhile, in order to prevent the held image signals S1, S2, . . . , Snfrom leaking, a storage capacity 5 is provided to be parallel to theliquid crystal capacity. In order to form the storage capacity 5, acapacity line 4 is formed along the scan line 2. The capacity line 4 isconnected to a common potential line (COM) and is held withpredetermined potential.

As shown in FIG. 3, the element substrate 20 includes a light shieldinglayer 22, an insulation layer 23, the TFT 24, an insulation layer 25, alight shielding layer 26, an insulation layer 27, the pixel electrode28, and an oriented film 29 on a substrate 21. The substrate 21 isformed of, for example, a transparent material such as glass or quartz.

The light shielding layer 22 is formed of, for example, a lightshielding material such as Mo (molybdenum), W (tungsten), Ti (titanium),TiN (titanium nitride), or Cr (chromium). The light shielding layer 22is formed in a lattice shape so as to overlap with the light shieldinglayer 26 in the upper layer in a planar view. The light shielding layer22 and the light shielding layer 26 are arranged to interpose the TFT 24in the thickness direction (Z direction) of the element substrate 20.The light shielding layer 22 overlaps with at least channel area of theTFT 24 in a planar view.

When the light shielding layer 22 and the light shielding layer 26 areprovided, light incident to the TFT 24 is suppressed. An area (inside ofan opening 22 a) which is enclosed by the light shielding layer 22 andan area (inside of an opening 26 a) which is enclosed by the lightshielding layer 26 are areas through which light passes in the pixel P.Meanwhile, the light shielding layer 22 includes a plurality of lightshielding films, and may be formed in a lattice shape to compensate witheach other.

The insulation layer 23 is provided to cover the substrate 21 and thelight shielding layer 22. The insulation layer 23 is formed of, forexample, an inorganic material such as SiO₂.

The TFT 24 is formed on the insulation layer 23. The TFT 24 is aswitching element which drives the pixel electrode 28. The TFT 24includes a semiconductor layer which is not shown in the drawing, thegate electrode, the source electrode, and the drain electrode. In thesemiconductor layer, a source area, a channel area, and a drain area areformed. On the boundary surface between the channel area and the sourcearea or between the channel area and the drain area, a Lightly DopedDrain (LDD) area may be formed.

The gate electrode is formed in an area which overlaps with the channelarea of the semiconductor layer in the element substrate 20 through apart (gate insulation film) of the insulation layer 25 in a planar view.Although not shown in the drawing, the gate electrode is electricallyconnected to the scan line which is arranged on a lower layer sidethrough a contact hole, and control is performed such that the TFT 24 isturned on or off when the scan signal is applied.

The insulation layer 25 is provided to cover the insulation layer 23 andthe TFT 24. The insulation layer 25 is formed of, for example, aninorganic material such as SiO₂. The insulation layer 25 includes a gateinsulation film which insulates between the semiconductor layer and thegate electrode of the TFT 24. Irregularities, which are generated due tothe TFT 24, on a surface is reduced by the insulation layer 25. Thelight shielding layer 26 is provided on the insulation layer 25.Further, the insulation layer 27, which is formed of an inorganicmaterial, is provided to cover the insulation layer 25 and the lightshielding layer 26.

The pixel electrode 28 is provided to correspond to the pixel P on theinsulation layer 27. The pixel electrode 28 is provided in an area whichoverlaps with the opening 22 a of the light shielding layer 22 and theopening 26 a of the light shielding layer 26 in a planar view. The pixelelectrode 28 is formed of, for example, a transparent conductive filmsuch as Indium Tin Oxide (ITO) or Indium Zinc Oxide. The oriented film29 is provided to cover the pixel electrode 28.

Meanwhile, the TFT 24 and an electrode or a wiring (not shown in thedrawing), which supplies an electrical signal to the TFT 24, areprovided in an area which overlaps with the light shielding layer 22 andthe light shielding layer 26 in a planar view. The electrode, the wiringand the like may be configured to combine with the light shielding layer22 and the light shielding layer 26.

The counter substrate 30 includes a microlens array substrate 10, anoptical path adjustment layer 31, a light shielding layer 32, aprotective layer 33, the common electrode 34, and an oriented film 35.

Microlens Array Substrate

The microlens array substrate 10 includes a substrate 11 and a lenslayer 14 as a light transmission layer. The microlens array substrate 10is arranged such that a side of the lens layer 14 faces the elementsubstrate 20.

The substrate 11 is formed of, for example, an inorganic material, suchas glass or quartz, which has optical transparency. The substrate 11includes a plurality of recesses 12 and a recess 13 which are formed ona surface which faces the element substrate 20. The plurality ofrecesses 12 are provided in the display area B and a dummy area D whichsurrounds the display area B. In the display area B, the plurality ofrecesses 12 are arranged to correspond to the respective pixels P. Inthe display area B, the plurality of recesses 12 may be provided toconnect each other or provided apart from each other.

When the dummy area D, in which the recesses 12 are arranged is providedon the outside of the display area B, is provided, evenness of thesurface of the lens layer 14, that is, the surface of the microlensarray substrate 10 is improved in an outer peripheral portion of thedisplay area B. Therefore, it is possible to cause the layer thicknessof the liquid crystal layer 40 to be uniform in the display area B andit is possible to cause an optical condition, such as refraction ofincident light, to be same, and thus it is possible to improve the imagequality of the liquid crystal device 1. Meanwhile, the dummy area D isan area in which light is shielded by the light shielding layers 22, 26,and 32 and which does not contribute to the display. In addition, theTFT 24 of a dummy pixel may be provided to correspond to the recess 12of the dummy area D. The recess 12 of the dummy area D may be providedin a plurality of rows along the edge of the display area B.

It is assumed that an area which includes the display area B and thedummy area D is a first area F. The pixels P are virtually arranged inthe dummy area D at the same pitch as the display area B. The pluralityof recesses 12 are arranged in the display area B and the dummy area Dat an arrangement pitch corresponding to the arrangement pitch of thepixel P. Parts of the recesses 12, which are arranged on a side of anoutermost peripheral area G of the dummy area D, are connected to theparts of the recess 13. The positions of the end parts of the pixels Pcorresponding to the recesses 12, which are arranged on the side of theoutermost peripheral area G, form the outer edge of the dummy area D andbecome the outer edge of the first area F.

An area which surrounds the first area F (dummy area D) is a peripheralarea G. The positions of the end parts of the pixels P corresponding tothe recesses 12, which are arranged on the side of the outermostperipheral area G, form an inner edge of the peripheral area G. Theperipheral area G is provided with a groove part 15 which includes abottom surface 15 a formed to be depressed from a surface 11 a (refer toFIG. 4B) as a first surface of the substrate 11 along the outer edge ofthe first area F (dummy area D). The recess 13 is provided along theouter edge of the first area F, and is arranged across a boundary part Cbetween the first area F (dummy area D) and the peripheral area G.

The recesses 12 and the recess 13 are formed in a substantially curvedsurface shape which tapers from a side of the liquid crystal layer 40toward the base thereof. The recesses 12 and the recess 13 include across-sectional shape which has, for example, a substantially sphericalsurface shape. However, the cross-sectional shape may be a shape whichincludes a base having a substantially plat portion, or a shape whichincludes a peripheral part having a taper shaped portion. Meanwhile,some parts of the recesses 12, which are provided in the dummy area D,and a part of the recess 13, which is provided across the boundary partC between the dummy area D and the peripheral area G, are connected toeach other. When a plurality of recesses 12 are provided in the dummyarea D, at least a part of the recesses 12 which are arranged in theoutermost peripheral area G is connected to at least a part of therecess 13.

The lens layer 14 is provided to cover the substrate 11 and to bury theplurality of recesses 12 and the recess 13. The lens layer 14 is formedof a material which has optical transparency and which has aphotorefractive index different from the substrate 11. Morespecifically, the lens layer 14 is formed of an inorganic material whichhas the photorefractive index higher than the substrate 11. As such aninorganic material, for example, Silicon Oxy-nitride (SiON), alumina(Al₂O₃), borosilicate glass, and the like may be provided.

With the lens layer 14 which buries the plurality of recesses 12, convexmicrolenses ML are formed to correspond to the respective pixels P. Inaddition, a microlens array MLA is formed by the plurality ofmicrolenses ML. Since the inorganic material which is used as a lensmaterial of the lens layer 14 has excellent tolerance for light or hightemperature rather than the resin material, it is possible to improvethe reliability of the microlenses ML.

The optical path adjustment layer 31 is provided to cover the microlensarray substrate 10. The optical path adjustment layer 31 is formed of,for example, an inorganic material which has approximately the samerefractive index as the substrate 11. The optical path adjustment layer31 has functions to planarize the surface of the microlens arraysubstrate 10 and adjust distances from the microlenses ML to the lightshielding layers 22 and 26 to desired values.

The light shielding layer 32 is provided in the dummy area D and theperipheral area G. The light shielding layer 32 may be also providedwithin the display area B, and may be formed in a lattice shape, anisland shape, a stripe shape, or the like so as to overlap with thelight shielding layers 22 and 26 of the element substrate 20 in a planarview. The protective layer 33 may be provided to cover the optical pathadjustment layer 31 and the light shielding layer 32. The protectivelayer 33 covers the light shielding layer 32 such that a surface of thecommon electrode 34 on a side of the liquid crystal layer 40 isplanarized.

The common electrode 34 is provided to cover the protective layer 33.The common electrode 34 is provided across the plurality of pixels P.The common electrode 34 is formed of, for example, a transparentconductive film such as Indium Tin Oxide (ITO) or Indium Zinc Oxide(IZO). The oriented film 35 is provided to cover the common electrode34.

The liquid crystal layer 40 is interposed between the oriented film 29on the side of the element substrate 20 and the oriented film 35 on theside of the counter substrate 30. The liquid crystal layer 40 is formedof liquid crystal which has positive or negative dielectric anisotropy.The liquid crystal which forms the liquid crystal layer 40 modulateslight in such a way that the orientation or order of molecular assemblychanges due to a level of a voltage to be applied, thereby enabling tonedisplay. For example, in a case of a normally white mode, atransmittance for incident light decreases according to a voltage whichis applied in units of each pixel P. In a case of normally black mode,the transmittance for incident light increases according to the voltagewhich is applied in units of each pixel P, and light which has contrastaccording to an image signal is emitted from the liquid crystal device 1as a whole.

In the liquid crystal device 1, for example, light, which is emittedfrom a light source or the like, is incident from a side of the countersubstrate 30 (substrate 11), which includes the microlenses ML, isrefracted by the microlenses ML, and then condensed. For example, inlight which is incident to the microlenses ML from the side of thesubstrate 11, incident light L1, which is incident along an optical axispassing through a planar center of an area of the pixel P, goes straightthrough the microlenses ML and is incident to the liquid crystal layer40, passes through the liquid crystal layer 40, and is emitted to theside of the element substrate 20.

If incident light L2, which is incident to the peripheral part of themicrolenses ML from an area overlapped with the light shielding layer 26on the outer side than the incident light L1 in the planar view,straightly propagates, is shielded by the light shielding layer 26 asshown using a dotted line. However, due to the difference in thephotorefractive index between the substrate 11 and the lens layer 14,incident light L2 is refracted toward a planar central side of the areaof the pixels P. In the liquid crystal device 1, it is possible to causethe incident light L2, which is shielded by the light shielding layer 26when straightly propagating, to be incident into the opening area(openings 26 a) of the pixels P due to the converging operation of themicrolenses ML and to pass through the liquid crystal layer 40. As aresult, it is possible to cause the amount of light element emitted fromthe side of the substrate 20 to be large, and thus it is possible toincrease utilization efficiency of light.

Meanwhile, since the lens layer 14 has a higher photorefractive indexthan the substrate 11, stay light L3, which is incident to the bottomsurface 15 a of the groove part 15 from a side part toward the upperside in an oblique direction, is totally reflected on the boundarysurface of the lens layer 14 and the substrate 11, and is directed tothe side of the liquid crystal layer 40 if an incident angle for thebottom surface 15 a is equal to or greater than a critical angle.However, as shown in FIG. 3, since light is shielded in the lightshielding layer 32, light is not incident to the display area B. Inaddition, although light L4, which is incident to the recess 13 from thesame direction as the stay light L3, is refracted on the boundarysurface of the lens layer 14 and the substrate 11, light L4 is notincident to the liquid crystal layer 40 because light L4 goes toward theupper side in the oblique direction.

In contrast, if the recess 13 is not provided and the bottom surface 15a of the groove part 15 is present up to the boundary part C of thefirst area F in the peripheral area G and if stay light L3 is incidentto the bottom surface 15 a in the vicinity of the boundary part C and istotally reflected on the boundary surface of the lens layer 14 and thesubstrate 11, there is a problem in that the stay light L3, which isreflected and goes toward the side of the liquid crystal layer 40, isnot shielded by the light shielding layer 32 and is incident to thedisplay area B. In the liquid crystal device 1 according to theembodiment, the recess 13 is provided in the peripheral area G, and thusit is possible to prevent the stay light L3, which is incident to thebottom surface 15 a in the vicinity of the boundary part C, from beingreflected and being incident to the display area B.

Method of Manufacturing Microlens Array Substrate

Substantially, a method of manufacturing the microlens array substrate10 according to the first embodiment will be described with reference toFIGS. 4A to 6B. FIGS. 4A to 5D are schematic cross-sectional diagramsillustrating the method of manufacturing the microlens array substrateaccording to the first embodiment. FIGS. 6A and 6B are schematicdiagrams illustrating a configuration of the first mask layer which isused for a process to manufacture the microlens array substrateaccording to the first embodiment. More specifically, FIG. 6A is aschematic plan view illustrating the configuration of the first masklayer, and FIG. 6B is a schematic cross-sectional diagram illustratingthe configuration of the first mask layer.

In FIG. 6A, the upside and downside of the direction (Z direction)viewed in a plane manner is inversed with regard to FIG. 1. Each ofFIGS. 4A to 5D and FIG. 6B corresponds to a cross-sectional diagramtaken along a line VIB-VIB of FIG. 6A. In addition, in description ofthe method of manufacturing the microlens array substrate, the lowerpart side (Z direction) of FIG. 6B is called a “lower part”.

Meanwhile, although not shown in the drawing, in the process tomanufacture the microlens array substrate 10, the process is performedon a large-sized substrate (mother board) in which it is possible toacquire a plurality of pieces of the microlens array substrates 10, themother board is finally cut and separated, and thus a plurality ofmicrolens array substrates 10 are acquired. Therefore, in each processwhich will be described blow, a process is performed on a state of themother board which is acquired before being separated. However, here, aprocess, which is performed on the individual microlens array substrate10 of the mother board, will be described.

First, as shown in FIG. 4A, a mask layer 71 is formed as a second masklayer on the surface 11 a of the substrate 11 which is formed of quartzand has optical transparency. The mask layer 71 is formed to cover thefirst area F (the display area B and the dummy area D) and expose theperipheral area G in the surface 11 a of the substrate 11 by, forexample, performing patterning using a photolithography method or thelike in such a way as to provide a resist layer on an upper layer of themask layer 71, and performing an anisotropic etching (dry etching)process using the resist layer as an etching mask.

Substantially, as shown in FIG. 4B, the anisotropic etching (dryetching) process is performed on the peripheral area G, which is notcovered by the mask layer 71, in the surface 11 a of the substrate 11.Therefore, the groove part 15, which is depressed from the surface 11 aof the substrate 11 toward the lower part, is formed to surround thefirst area F along the outer edge of the first area F. The groove part15 is formed over, for example, the whole area of the peripheral area G.

Meanwhile, an end part of the separated microlens array substrate 10 isthe outer edge of the peripheral area G. Therefore, the groove part 15is formed up to the end part of the microlens array substrate 10. Thegroove part 15 includes a bottom surface 15 a which is substantiallyparallel to the surface 11 a of the substrate 11, and a side wall 15 bwhich is positioned in a boundary part C between the first area F andperipheral area G and which connects the surface 11 a to the bottomsurface 15 a. After the groove part 15 is formed, the mask layer 71 isremoved from the substrate 11.

In a process to form the groove part 15 shown in FIG. 4B, an isotropicetching (wet etching) process can be performed. However, in theisotropic etching process, etching proceeds to spread toward a lowerpart and a lateral side from a portion in which the surface 11 a isexposed. Therefore, there are cases in which the bottom surface 15 a ofthe groove part 15 to be formed is not a flat surface and a case inwhich etching is performed up to a portion covered by the mask layer 71and thus the groove part 15 enters the first area F beyond the boundarypart C.

In contrast, when the anisotropic etching process is performed as in theembodiment, evenness of the bottom surface 15 a of the groove part 15 isimproved and, for example, the positional precision of the side wall 15b of the groove part 15 is improved, compared to a case in which theisotropic etching is performed. Meanwhile, when the anisotropic etchingprocess is performed, the corner of the bottom surface 15 a and the sidewall 15 b is steep, compared to the case in which the isotropic etchingis performed.

Meanwhile, in the embodiment, an installed anisotropic etching processapparatus is used for a process to manufacture the TFT 24, and thus newintroduction of the isotropic etching process apparatus is suppressed.Therefore, in a process in which the anisotropic etching process can beapplied, the anisotropic etching process is performed.

Substantially, as shown in FIG. 4C, a mask layer 72 is formed as thefirst mask layer throughout the first area F and the peripheral area Gto cover the side of the surface 11 a of the substrate 11. The masklayer 72 can be formed of, for example, poly-silicon, using a ChemicalVapor Deposition (CVD) method, a sputtering method, or the like. Themask layer 72 is formed to cover the surface 11 a of the substrate 11,and the side wall 15 b and the bottom surface 15 a of the groove part15.

Subsequently, as shown in FIG. 4D, patterning is performed on the masklayer 72 using the photolithography method, openings 73 are formed asthe plurality of first openings in the first area F, and an opening 74is formed as a second opening along the outer edge of the first area Fin the peripheral area G.

As shown in FIG. 6A, the respective openings 73 are provided tocorrespond to the planar central positions of the recesses 12 (shown bydotted lines in FIG. 6A) which are formed in a subsequent process, thatis, the planar central positions of the pixels P (refer to FIG. 3).Therefore, the plurality of openings 73 are arranged at a pitchcorresponding to an arrangement pitch of the pixels P. In addition, theopening 74 is provided to surround the periphery of the first area F.The width of the opening 74 is substantially the same as the diameter ofthe opening 73. The surface 11 a of the substrate 11 is exposed in theopenings 73, and the bottom surface 15 a of the groove part 15 isexposed in the openings 74.

As shown in FIG. 6B, the opening 74 is provided on the bottom surface 15a of the groove part 15. Here, when it is assumed that a distancebetween a corner, in which the bottom surface 15 a and the side wall 15b of the groove part 15 are connected in the boundary part C, and theplanar center of the opening 74 is E, that a step (distance in the Zdirection) between the surface 11 a of the substrate 11 and the bottomsurface 15 a of the groove part 15 is H, and that the depth (distance inthe Z direction from the surface 11 a to the bottom part) of the recess12 to be formed is M, it is preferable that M-HE. That is, it ispreferable that the distance E between the corner, in which the bottomsurface 15 a and the side wall 15 b of the groove part 15 are connected,and the planer center of the opening 74 be equal to or less than adifference between the step H between the surface 11 a and the bottomsurface 15 a of the groove part 15 and the depth M of the recess 12.

When the opening 74 is arranged in the position as described above, in aprocess to remove the mask layer 72 which will be described later, it ispossible to properly remove the mask layer 72 even in the corner of thebottom surface 15 a and the side wall 15 b of the groove part 15 in theboundary part C. Meanwhile, the distance E between the boundary part Cand the opening 74 is greater than the film thickness of the mask layer72. If the distance E is equal to or less than the film thickness of themask layer 72, the opening 74 is formed in a film thickness portioncorresponding to the sum of the step H and the film thickness of themask layer 72, and thus it is difficult to form the opening 74.

Substantially, as shown in 5A, the isotropic etching process such as wetetching is performed on the substrate 11 using, for example, an etchingsolution such as hydrofluoric acid solution, through the plurality ofopenings 73 and the opening 74 in the mask layer 72. When the isotropicetching process is performed, the plurality of recesses 12 are formed toextend toward the lower part from the surface 11 a while centering onthe plurality of openings 73 in the first area F. The recess 12 isformed in a concentric shape which includes the opening 73 as a centerin the planar view (refer to FIG. 6A). Adjacent recesses 12 of theplurality of recesses 12 may be connected to each other or may beseparated from each other.

In addition, in the peripheral area G, a recess 13, which includes theopening 74 as a center and which is continued along the outer edge ofthe first area F, is formed. The recess 13 is formed in a groove shapealong the opening 74 (refer to FIG. 6A) in the planar view. As theetching process is progressed, the recess 13 extends from the bottomsurface 15 a toward the lower part, extends toward an upper side thanthe side part and the bottom surface 15 a, and is formed across theperipheral area G and the first area F. Therefore, the recess 13 isconnected to the recess 12 in the adjacent dummy area D. As a result,since a part of the substrate 11 on the side of the boundary part C ofthe side wall 15 b (refer to FIG. 6B) and the bottom surface 15 a of thegroove part 15 is removed, a cavity part is generated on the lower partand the side part of the mask layer 72 at the corner of the part whichis formed on the bottom surface 15 a and the part which is formed on theside wall 15 b in the mask layer 72. That is, the mask layer 72 is in astate in which the mask layer 72 is floated in the boundary part Cbetween the peripheral area G and the first area F.

Substantially, when the dry etching process is performed on the masklayer 72 as shown in FIG. 5B, the mask layer 72 is removed from thesubstrate 11. Therefore, the recesses 12 which are formed in the firstarea F, the recess 13 which is formed across the boundary part C betweenthe peripheral area G and the first area F, and the bottom surface 15 aare exposed.

Here, although the recess 13 is provided in the substrate 11 in theembodiment, a case in which the recess 13 is not provided is supposed.FIG. 10A illustrates a comparative example when the recess 13 is notformed. When the recess 13 is not formed as in the comparative exampleshown in FIG. 10A, a surface area per unit volume of the mask layer 72is small at the corner of the bottom surface 15 a and the side wall 15b, compared to other portions. Therefore, there is a problem in that apart of the mask layer 72 is not removed and remains. When a part of themask layer 72 remains, there are cases in which the lens layer 14, whichwill be subsequently formed, is peeled together with the remaining masklayer 72 and in which cracks appear in the lens layer 14 because stressis applied to the remaining mask layer 72.

In the embodiment, as shown in FIG. 5A, when the recess 13 is formed,the cavity part which is continued along the outer edge of the firstarea F on the lower part and the side part of the mask layer 72 isgenerated at the corner of the bottom surface 15 a and the side wall 15b (refer to FIG. 6B), and an opening 74 is provided in the vicinity ofthe corner. Therefore, since the surface area of a portion in which themask layer 72 is exposed is large at the corner of the bottom surface 15a and the side wall 15 b, it is possible to perform removal such that apart of the mask layer 72 does not remain.

Meanwhile, in a process to form the groove part 15, it is possible toperform the isotropic etching (wet etching) process. When the isotropicetching process is performed, an etching solution goes from the opening74 to the recess 13, and thus it is possible to perform removal suchthat a part of the mask layer 72 does not remain at the corner of thebottom surface 15 a and the side wall 15 b similarly to the case inwhich the anisotropic etching is performed.

Substantially, as shown in FIG. 5C, a light transmission material layer14 a is formed by accumulating a light transmission material, which isformed of an inorganic material having a refractive index higher thanthat of the substrate 11, so as to cover the surface 11 a of thesubstrate 11 and bury the plurality of recesses 12 and the recess 13. Itis possible to form the light transmission material layer 14 a using,for example, the CVD method. The light transmission material layer 14 ais formed throughout the first area F and the peripheral area G. Thestep is reflected in the upper surface of the light transmissionmaterial layer 14 a due to the recesses 12 and the recess 13.

Substantially, as shown in FIG. 5D, a planarizing process is performedon the light transmission material layer 14 a. In the planarizingprocess, the light transmission material layer 14 a is planarized bypolishing the upper surface of the light transmission material layer 14a using, for example, a Chemical Mechanical Polishing (CMP) process orthe like. Therefore, the upper surface of the light transmissionmaterial layer 14 a is planarized and the lens layer 14 is formed.Meanwhile, a planarizing processing method in the planarizing process isnot limited to the CMP process, and an etch back method may be used.

As a result, the microlenses ML are formed by the lens layer 14 whichburies the plurality of recesses 12 and the recess 13, and thus themicrolens array substrate 10 which includes the microlens array MLA iscompleted. Meanwhile, sine the microlenses ML corresponding to therecesses 12 and the recess 13, which are arranged in the dummy area D,overlap with the light shielding layers 22, 26, and 32 (refer to FIG. 3)in the planar view, the microlenses ML do not function as microlenses.

However, the groove part 15 is provided in the substrate 11 in theembodiment, and the embodiment is compared with a case in which thegroove part 15 is not provided. FIG. 10B illustrates a comparativeexample when the groove part 15 is not formed. When the groove part 15is not formed as in the comparative example shown in FIG. 10B, the uppersurface of the light transmission material layer 14 a is high in theperipheral area G in which the recesses are not formed compared to thefirst area F in which the plurality of recesses 12 are formed to be dugdown from the surface 11 a of the substrate 11, and thus a step isgenerated on the upper surface of the light transmission material layer14 a. If the step on the upper surface of the light transmissionmaterial layer 14 a is large, increase in man hour when the planarizingprocess is performed in the light transmission material layer 14 a ordecrease in evenness of the upper surface of the light transmissionmaterial layer 14 a are caused.

In the embodiment, as shown in FIG. 6B, the groove part 15 is formed inthe peripheral area G along the outer edge of the first area F in whichthe plurality of recesses 12 are arranged. Therefore, if the lighttransmission material layer 14 a is formed by accumulating the lighttransmission material so as to bury the plurality of recesses 12 whichcover the side of the surface 11 a of the substrate 11 as shown in FIG.5C, the step between the first area F which is generated on the uppersurface of the light transmission material layer 14 a and the peripheralarea G of the periphery is reduced by the step H between the surface 11a and the bottom surface 15 a and becomes less, compared to the case inwhich the groove part 15 is not formed as in the comparative exampleshown in FIG. 10B. Therefore, in the process to planarize the uppersurface of the light transmission material layer 14 a, it is possible toreduce the man hour when the planarizing process is performed and toimprove the evenness of the upper surface of the light transmissionmaterial layer 14 a.

As described above, according to the method of manufacturing themicrolens array substrate 10 according to the first embodiment, evenwhen the groove part 15 is provided in the outer edge of the first areaF in order to reduce the step on the upper surface of the lighttransmission material layer 14 a, it is possible to perform removal suchthat a part of the mask layer 72 does not remain at the corner of thebottom surface 15 a and the side wall 15 b. Therefore, it is possible toimprove the evenness of the upper surface of the lens layer 14 and it ispossible to provide the microlens array substrate 10 with the improvedmanufacturing yield and high quality.

Second Embodiment

In a second embodiment, a configuration of a second recess, which isformed across the boundary part C between the first area F and theperipheral area G, is different from that in the first embodiment butthe other configurations are substantially the same. Therefore,differences in the method of manufacturing the microlens array substratefrom that of the first embodiment will be described. FIGS. 7A and 7B areschematic diagrams illustrating a configuration of a first mask layerwhich is used for a process to manufacture a microlens array substrateaccording to the second embodiment. More specifically, FIG. 7A is aschematic plan view illustrating the configuration of the first masklayer, and FIG. 7B is a schematic cross-sectional diagram illustratingthe configuration of the first mask layer. FIG. 7B corresponds to thecross-sectional diagram taken along a line VIIB-VIIB of FIG. 7A.

Method of Manufacturing Microlens Array Substrate

As shown in FIG. 7A, in the second embodiment, a plurality of openings76 are provided as second openings in the mask layer 75 as the firstmask layer using a process to form the plurality of recesses 12 (referto FIG. 5A). The openings 76 are arranged in plural in the peripheralarea G along the outer edge of the first area F. The diameter of each ofthe openings 76 is substantially the same as the diameter of each of theopenings 73. Therefore, the plane area of the recess 16 which is formedbased on a single opening 76 as a center is substantially the same asthe plane area of the recess 12 which is formed based on the opening 73as a center.

Here, it is preferable that an interval K2 between the openings 76 besmaller than an interval K1 between the openings 73. For example, if theinterval K2 between the openings 76 is the same as the interval K1between the openings 73, a cavity part is generated in the lower partand the side part of the mask layer 75 at the corner of the bottomsurface 15 a and the side wall 15 b for each formed recess 16. However,a portion which does not include the cavity part remains between therecesses 16.

If the interval K2 between the openings 76 is smaller than the intervalK1 between the openings 73, the plurality of recesses 16 are formed in astate in which adjacent recesses 16 are connected to each other.Therefore, as the interval K2 between the openings 76 is small, theportion which does not include the cavity part between the recesses 16is small. Accordingly, it is possible to provide the cavity partconnected along the outer edge of the first area F in the lower part andthe side part of the mask layer 75 at the corner of the bottom surface15 a and the side wall 15 b.

Therefore, similarly to the first embodiment, in a process to remove themask layer 75 from the substrate 11, it is possible to perform removalsuch that a part of the mask layer 75 does not remain at the corner ofthe bottom surface 15 a and the side wall 15 b in the second embodiment.Therefore, it is possible to improve the evenness of the upper surfaceof the lens layer 14, and it is possible to provide the microlens arraysubstrate 10 with the improved manufacturing yield and high quality.

Meanwhile, as shown in FIG. 7B, a cross-sectional shape taken along theline VIIB-VIIB of FIG. 7A in the second embodiment is substantially thesame as that in the first embodiment shown in FIG. 6B.

Third Embodiment Electronic Apparatus

Substantially, an electronic apparatus according to a third embodimentwill be described with reference to FIG. 8. FIG. 8 is a schematicdiagram illustrating a configuration of a projector as an electronicapparatus according to the third embodiment.

As shown in FIG. 8, the projector (projection type display apparatus)100 as the electronic apparatus according to the third embodimentincludes a polarization lighting apparatus 110, two dichroic mirrors 104and 105 as light separating elements, three reflecting mirrors 106, 107,and 108, five relay lenses 111, 112, 113, 114, and 115, three liquidcrystal light valves 121, 122, and 123, a cross dichroic prism 116 as alight composition element, and a projection lens 117.

The polarization lighting apparatus 110 includes, for example, a lampunit 101 as a light source which includes a white light source, such asa ultrahigh pressure mercury lamp or a halogen lamp, an integrator lens102, and a polarization conversion element 103. The lamp unit 101, theintegrator lens 102, and the polarization conversion element 103 arearranged along a system optical axis Lx.

The dichroic mirror 104 reflects red light (R) in polarization lightflux emitted from the polarization lighting apparatus 110, and causesgreen light (G) and blue light (B) to pass through. The other onedichroic mirror 105 reflects green light (G) which passed through thedichroic mirror 104 and causes blue light (B) to pass through.

Red light (R) which is reflected in the dichroic mirror 104 is reflectedin the reflecting mirror 106, and is incident to the liquid crystallight valve 121 through the relay lenses 115. Green light (G) which isreflected in the dichroic mirror 105 is incident to the liquid crystallight valve 122 through the relay lens 114. Blue light (B) which passesthrough the dichroic mirror 105 is incident to the liquid crystal lightvalve 123 through a light guiding system which includes the three relaylenses 111, 112, and 113 and the two reflecting mirrors 107 and 108.

The transmission type liquid crystal light valves 121, 122, and 123 asoptical modulation elements are arranged to respectively face incidentsurfaces for respective colored light of the cross dichroic prism 116.The colored light incident to the liquid crystal light valves 121, 122,and 123 is modulated based on image information (image signal), and isemitted toward the cross dichroic prism 116.

The cross dichroic prism 116 includes four right-angle prisms which arebonded to each other, and includes a dielectric multi-layer film whichreflects red light and a dielectric multi-layer film which reflects bluelight therein. The dielectric multi-layer films are formed to cross eachother. Three colored light is composed by the dielectric multi-layerfilms, and light which expresses a color image is composed. The composedlight is projected on a screen 130 by the projection lens 117 which isthe projection optical system and the image is shown by being enlarged.

The liquid crystal device 1, which includes the microlens arraysubstrate 10 manufactured using the above-described manufacturing methodaccording to the first embodiment or the second embodiment, is appliedto the liquid crystal light valve 121. The liquid crystal light valve121 is arranged with a gap between a pair of polarization elements whichare arranged in cross-nicol alignment on the incident side and emissionside of the color light. The other liquid crystal light valves 122 and123 are arranged in the same manner.

According to such a configuration of the projector 100, even though theplurality of pixels P are arranged with high definition, the liquidcrystal device 1, which is capable of effectively using incident colorlight, is provided, and thus it is possible to provide the projector 100with high quality and brightness.

The above-described embodiments only show aspects of the invention, andarbitrary modification and application are possible without departingfrom the scope of the invention. As modification examples, for example,examples below may be conceivable.

First Modification Example

In the method of manufacturing the microlens array substrate accordingto the above embodiments, the openings 74 and 76 as the second openings,which are formed in the mask layers 72 and 75 as the first mask layer,are configured to be arranged on the groove part 15 in the peripheralarea G. However, the invention is not limited to such a form. Forexample, the second openings may be configured to be arranged in thefirst area F. FIGS. 9A and 9B are schematic cross-sectional diagramsillustrating a method of manufacturing a microlens array substrateaccording to a first modification example. Meanwhile, a process shown inFIG. 9A corresponds to the process shown in FIG. 4D according to thefirst embodiment, and a process shown in FIG. 9B corresponds to theprocess shown in FIG. 5A according to the first embodiment.

As shown in FIG. 9A, in the method of manufacturing the microlens arraysubstrate according to the first modification example, in a mask layer77 as a first mask layer, openings 78 as the second openings are formedin the first area F. More specifically, the openings 78 are formed alongthe outer edge of the display area B in a position in the vicinity ofthe boundary part C of the dummy area D and the peripheral area G. Theopenings 78 may be provided in succession similarly to the openings 74according to the first embodiment, and may be provided in pluralsimilarly to the openings 76 according to the second embodiment.Meanwhile, the plurality of openings 73 are formed in the display area Bsimilarly to the embodiment.

As shown in FIG. 9B, when the isotropic etching process is performed onthe substrate 11 through the mask layer 77, the continued recesses 17 orthe plurality of recesses 17 are formed along the outer edge of thefirst area F using the openings 78 as the centers thereof in the dummyarea D. The recesses 17 are formed across the boundary part C betweenthe first area F (dummy area D) and the peripheral area G. Therefore,even in a configuration according to the first modification example, acavity part in which the substrate 11 is removed is generated in thelower part and the side part of the mask layer 77 at the corner of thebottom surface 15 a and the side wall 15 b. Therefore, similarly to theembodiments, in a process to remove the mask layer 77 from the substrate11, it is possible to perform removal such that a part of the mask layer77 does not remain at the corner of the bottom surface 15 a and the sidewall 15 b. Therefore, it is possible to improve the evenness of theupper surface of the lens layer 14 and it is possible to provide themicrolens array substrate 10 with the improved manufacturing yield andwhich high quality.

However, compared to the first modification example, the recess 13,which is formed to correspond to the opening 74, is formed in a lowerpart than the corner of the bottom surface 15 a and the side wall 15 bof the groove part 15 in the embodiment. Therefore, in the embodiment, alarger cavity part is generated in the lower part of the mask layer 72at the corner, and thus it is possible to more properly remove the firstmask layer.

Meanwhile, in the first modification example, the openings 78 areprovided on the surface 11 a of the substrate 11 in the mask layer 77,the openings 78 and the openings 73 are formed at the same height.Therefore, in a case of exposure when the openings 73 and the openings78 are formed on the mask layer 77, it is possible to cause a distancefrom an exposure machine to positions where the openings are formed tobe substantially the same between the openings 73 and the openings 78.Therefore, it is possible to cause the positions and the precision ofthe sizes of the diameters of the openings 78 to be equivalent to thoseof the openings 73.

Second Modification Example

In the embodiments, the lens layer 14 is formed of a material which hasa higher photorefractive index than the substrate 11. However, theinvention is not limited to such a form. The lens layer 14 may be formedof a material which has a lower photorefractive index than the substrate11.

Third Modification Example

In the embodiments, the microlens array substrate 10 is included in thecounter substrate 30. However, the invention is not limited to theembodiment. For example, the microlens array substrate 10 may beconfigured to be included in the element substrate 20. In addition, themicrolens array substrate 10 may be included in both the elementsubstrate 20 and the counter substrate 30.

Fourth Modification Example

In the embodiments and the modification examples, the microlens arraysubstrate 10 is configured such that the microlenses ML (recesses 12)are arranged in the matrix shape in the display area B. However, theinvention is not limited such embodiments. The array of the microlensesML corresponds to the array of the pixels P, and may be, for example, adifferent array such as honeycomb array.

Fifth Modification Example

An electronic apparatus to which the liquid crystal device according tothe embodiments can be applied is not limited to the projector 100. Theliquid crystal device 1 can be suitably used as, for example, a displayunit of information terminal equipment such as a projection type Head UpDisplay (HUD) or a direct-view Head Mounted Display (HMD), or anelectronic book, a personal computer, a digital steel camera, a liquidcrystal television, a viewfinder-type or direct-view monitor type videorecorder, a car navigation system, an electronic organizer, or a POS.

The entire disclosure of Japanese Patent Application No. 2013-201053,filed Sep. 27, 2013 is expressly incorporated by reference herein.

What is claimed is:
 1. A method of manufacturing a microlens arraysubstrate in which a plurality of microlenses are arranged in a firstarea, the method comprising: forming a groove part along an outer edgeof the first area on a first surface of a substrate; forming a firstmask layer to cover a side of the first surface of the substrate,forming a plurality of first openings corresponding to the plurality ofmicrolenses in the first area of the first mask layer, and formingsecond openings along the outer edge of the first area; performingisotropic etching on the substrate through the first mask layer, forminga plurality of first recesses corresponding to the plurality of firstopenings in the first area, and forming second recesses corresponding tothe second openings across an edge part on a side of the first area ofthe groove part; removing the first mask layer from the substrate;forming a light transmission material layer that has a refractive index,which is different from a refractive index of the substrate, to coverthe side of the first surface of the substrate and to bury the pluralityof first recesses and the second recesses; and planarizing an uppersurface of the light transmission material layer.
 2. The method ofmanufacturing a microlens array substrate according to claim 1, whereinthe forming of the groove part includes: forming a second mask layerthat covers the first area of the first surface of the substrate;forming the groove part by performing anisotropic etching on thesubstrate through the second mask layer; and removing the second masklayer.
 3. The method of manufacturing a microlens array substrateaccording to claim 1, wherein the removing of the first mask layerincludes performing anisotropic etching on the first mask layer.
 4. Themethod of manufacturing a microlens array substrate according to claim1, wherein the second openings are arranged to extend along the outeredge of the first area.
 5. The method of manufacturing a microlens arraysubstrate according to claim 1, wherein the forming of the secondopenings includes forming a plurality of second openings along the outeredge of the first area, and wherein an interval between the plurality ofsecond openings is smaller than an interval between the plurality offirst openings.
 6. The method of manufacturing a microlens arraysubstrate according to claim 1, wherein the second openings are arrangedin an area which is overlapped with the groove part in a planar view. 7.The method of manufacturing a microlens array substrate according toclaim 6, wherein a distance between a boundary part and the secondopenings is equal to or less than a difference between a step of thefirst surface and the groove part and a depth of the first recess. 8.The method of manufacturing a microlens array substrate according toclaim 1, wherein the second openings are arranged in the first area. 9.A microlens array substrate comprising: a substrate; a plurality offirst recesses that are provided in a first area of a first surface ofthe substrate; a groove part that is provided along an outer edge of thefirst area; second recesses that are provided across a boundary partbetween the first area and the groove part; and a light transmissionlayer that has a refractive index, which is different from a refractiveindex of the substrate, and that is provided to cover the first surfaceof the substrate and to bury the plurality of first recesses and thesecond recesses.
 10. An electro-optic device comprising: a firstsubstrate; a second substrate that is arranged to face the firstsubstrate; an electro-optic layer that is arranged between the firstsubstrate and the second substrate; and the microlens array substrateaccording to claim 9 that is provided on at least one of the firstsubstrate and the second substrate.
 11. An electronic apparatuscomprising the electro-optic device according to claim 10.